Feature/rearrange casecontainer

[nbarlowATI]

First attempt to address #140 and #141 , in response to feedback from workshop using the prototype tool.

• Modify the Grid in CaseContainer - aim to add a new row, and divide the right side (below the header) into "top-right" and "bottom-right". <====. This is not yet working as hoped!
• Make the ItemView layer only appear in the bottom right.
• Make the ItemEditor only appear in the bottom right, and also make it just a Box, rather than a Layer, so that it is possible to click outside it when it is there.
• Remove the "Edit" button from the ItemViewer - instead, when the user clicks on a node, they get either the ItemViewer or the ItemEditor depending on whether they are in Editor mode.
• Remove the "Create xxx" buttons from ItemEditor - instead, have the buttons in the top right be contextual - if the ItemEditor box is visible, replace the existing buttons (e.g. Create new Goal, Exit Editor Mode, Export, ) with the buttons to create child nodes.
• Some logic to highlight nodes (turn them purple, with yellow outline and text) in utils.js - this seems to necessitate using the "loading" state, and imposing a short wait in order for the mermaid chart to render when removing the highlight.

Main current problem is the layout, particularly for the ItemEditor - this goes way off the bottom of the screen. Also, the buttons at the top are too squashed together.
Also, the highlighted node when in Edit mode only disappears when "submit" is clicked, not when the "close" button is clicked.

[coveralls]

Pull Request Test Coverage Report for Build 2376913715

• 102 of 221 (46.15%) changed or added relevant lines in 7 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-6.7%) to 81.036%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
eap_backend/eap_api/models.py	8	9	88.89%
eap_backend/eap_api/view_utils.py	54	104	51.92%
eap_backend/eap_api/views.py	17	85	20.0%

Files with Coverage Reduction	New Missed Lines	%
eap_backend/eap_api/views.py	2	55.44%

Totals
Change from base Build 2339861396:	-6.7%
Covered Lines:	923
Relevant Lines:	1139

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💛 - Coveralls